Semiconductor device

ABSTRACT

The semiconductor device includes a semiconductor element, a main lead and a resin package. The semiconductor element includes an obverse surface and a reverse surface spaced apart from each other in a thickness direction. The main lead supports the semiconductor element via the reverse surface of the semiconductor element. The resin package covers the entirety of the semiconductor element. The resin package covers the main lead in such a manner that a part of the main lead is exposed from the resin package. The semiconductor element includes a part that does not overlap the main lead as viewed in the thickness direction.

This application is a Continuation of U.S. Ser. No. 14/253,421, filedApr. 15, 2014 (now U.S. Pat. No. 9,236,317), which application isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a package type semiconductor device.

2. Description of the Related Art

Conventionally, a semiconductor device having a semiconductor elementsealed in a resin package has been proposed. For instance, thesemiconductor device disclosed in JP2012-190936A includes asemiconductor element, three leads, three wires and a resin package. Thesemiconductor element is placed on a mount surface of a main lead (oneof the three leads). The semiconductor element has a surface on whichthree electrodes are formed. These electrodes are connected to the threeleads via the three wires, respectively. The resin package covers theentirety of the semiconductor element, all of the three wires, and apart of each of the three leads. Each of the three leads has a part(terminal) projecting from the resin package.

In the conventional semiconductor device, the size of main lead islarger than that of the semiconductor element. Since the resin packagecovers the entirety of the main lead, the resin package is undesirablylarge relative to the semiconductor element, which hinders sizereduction of the semiconductor device.

SUMMARY OF THE INVENTION

The present invention has been conceived under the circumstancesdescribed above. It is therefore an object of the present invention toprovide a semiconductor device suitable for size reduction.

A semiconductor device provided according to a first aspect of thepresent invention includes a semiconductor element including an obversesurface and a reverse surface spaced apart from each other in athickness direction, a main lead supporting the semiconductor elementvia the reverse surface, and a resin package covering the semiconductorelement and the main lead. The main lead is exposed from resin package.The semiconductor element includes a part that does not overlap the mainlead as viewed in the thickness direction.

A semiconductor device provided according to a first aspect of thepresent invention includes a semiconductor element, a first and a secondbumps, a main lead, a first and a second wires, a first and a secondsubleads and a resin package.

The semiconductor element includes an obverse surface and a reversesurface spaced apart from each other in a thickness direction, a firstobverse surface electrode and a second obverse surface electrode formedon the obverse surface, and a reverse surface electrode formed on thereverse surface. The first bump and the second bump are formed on thefirst obverse surface electrode and the second obverse surfaceelectrode, respectively. The main lead includes a die pad to which thereverse surface electrode is electrically connected and a main-leadreverse surface terminal arranged on the opposite side of the die pad.The first sublead includes a first wire bonding portion connected to thefirst obverse surface electrode via the first wire and a first subleadreverse surface terminal provided on the opposite side of the first wirebonding portion. The second sublead includes a second wire bondingportion connected to the second obverse surface electrode via the secondwire and a second sublead reverse surface terminal provided on theopposite side of the second wire bonding portion. The resin packagecovers the semiconductor element and a part of each of the main lead,the first sublead and the second sublead. The resin package has a commonsurface from which the main lead reverse surface terminal, the firstsublead reverse surface terminal and the second sublead reverse terminalare exposed. The exposed surfaces of the main lead reverse surfaceterminal, the first sublead reverse surface terminal and the secondsublead reverse terminal face in the same direction.

According to the second aspect of the present invention, the main leadincludes a main-lead full-thickness portion extending from the die padto the main-lead reverse surface terminal and a main-lead eaved portionprojecting from the main-lead full-thickness portion in a directionperpendicular to the thickness direction. The die pad and thesemiconductor element overlap both of the main-lead full-thicknessportion and the main-lead eaved portion as viewed in the thicknessdirection. At least one of the first obverse surface electrode and thesecond obverse surface electrode overlaps the main-lead eaved portion.The first wire includes a first bonding portion bonded to the first wirebonding portion and a second bonding portion bonded to the first obversesurface electrode via the first bump. The second wire includes a firstbonding portion bonded to the second wire bonding portion and a secondbonding portion bonded to the second obverse surface electrode via thesecond bump.

Other features and advantages of the present invention will become moreapparent from detailed description given below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a semiconductor deviceaccording to a first embodiment of the present invention;

FIG. 2 is a plan view illustrating the semiconductor device of the firstembodiment;

FIG. 3 is a bottom view of the semiconductor device of the firstembodiment;

FIG. 4 is a sectional view taken along lines IV-IV in FIG. 2;

FIG. 5 is a sectional view taken along lines V-V in FIG. 2;

FIG. 6 is a sectional view illustrating a part of the semiconductordevice of the first embodiment;

FIG. 7 is a sectional view taken along lines VII-VII in FIG. 2;

FIG. 8 is a sectional view taken along lines VIII-VIII in FIG. 2;

FIG. 9 is a sectional view taken along lines IX-IX in FIG. 2;

FIG. 10 shows an enlarged image of a second bonding portion of thesemiconductor device of the first embodiment;

FIG. 11 is a sectional view illustrating a step of a method for makingthe semiconductor device of the first embodiment;

FIG. 12 is a perspective view illustrating a semiconductor deviceaccording to a second embodiment of the present invention;

FIG. 13 is a plan view illustrating the semiconductor device of thesecond embodiment;

FIG. 14 is a plan view illustrating a part of a semiconductor element ofthe first embodiment;

FIG. 15 is a plan view illustrating a variation of the semiconductordevice of the first embodiment;

FIG. 16 is a perspective view illustrating a semiconductor deviceaccording to a third embodiment of the present invention;

FIG. 17 is a perspective view illustrating a semiconductor deviceaccording to a third embodiment of the present invention;

FIG. 18 is a plan view illustrating the semiconductor device accordingto the third embodiment of the present invention;

FIG. 19 is a sectional view taken along XIX-XIX in FIG. 18;

FIG. 20 is a sectional view taken along XX-XX in FIG. 18;

FIG. 21 is a sectional view illustrating a part of the semiconductordevice of the third embodiment;

FIG. 22 is a sectional view taken along lines XXII-XXII in FIG. 18;

FIG. 23 is a sectional view taken along lines XXIII-XXIII in FIG. 18;

FIG. 24 is a sectional view taken along lines XXIV-XXIV in FIG. 18;

FIG. 25 is a plan view illustrating a part of a semiconductor element ofthe third embodiment;

FIG. 26 is a sectional view illustrating a step of a method for makingthe semiconductor device of the third embodiment;

FIG. 27 is a sectional view illustrating a step of a method for makingthe semiconductor device of the third embodiment;

FIG. 28 is a sectional view illustrating a step of a method for makingthe semiconductor device of the third embodiment;

FIG. 29 is a sectional view illustrating a step of a method for makingthe semiconductor device of the third embodiment;

FIG. 30 is a sectional view illustrating a step of a method for makingthe semiconductor device of the third embodiment;

FIG. 31 is a sectional view illustrating a step of a method for makingthe semiconductor device of the third embodiment;

FIG. 32 is an enlarged image of a second bonding portion of thesemiconductor device of the third embodiment;

FIG. 33 is a plan view illustrating a cutting step of a method formaking the semiconductor device of the third embodiment;

FIG. 34 is an X-ray image of the semiconductor device of the thirdembodiment; and

FIG. 35 is a plan view illustrating a semiconductor device according toa fourth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described below with referenceto the accompanying drawings.

A semiconductor device according to a first embodiment of the presentinvention is described below with reference to FIGS. 1-11.

The illustrated semiconductor device 101 includes a semiconductorelement 200, a main lead 300, a first sublead 400, a second sublead 500,a first wire 600, a second wire 700 and a resin package 800. In FIGS. 1and 2, the resin package 800 is indicated by double-dashed lines. Thesemiconductor device 101 is configured as a relatively small device thatcan be surface-mounted. For instance, the semiconductor device 101 isabout 0.4-0.8 mm in dimension in the direction x, about 0.2-0.6 mm indimension in the direction y and about 0.3-0.4 mm in dimension in thedirection z.

In the illustrated example, the semiconductor element 200 is configuredas a transistor. However, the present invention is not limited to this.For instance, a diode may be used as the semiconductor element of thesemiconductor device of the present invention.

The semiconductor element 200 includes an element body having an obversesurface 201 and a reverse surface 202, a first obverse surface electrode211, a second obverse surface electrode 212 and a reverse surfaceelectrode 220. The obverse surface 201 and the reverse surface 202 arespaced apart from each other in the direction z (thickness direction)and face in mutually opposite directions. For instance, thesemiconductor element 200 is about 300 μm in dimension in the directionx and about 300 μm in dimension in the direction y.

As shown in FIG. 14, the first obverse surface electrode 211 and thesecond obverse surface electrode 212 are formed on the obverse surface201 of the element body. Specifically, the obverse surface 201 is formedwith an electrode layer 213. Each of the first obverse surface electrode211 and the second obverse surface electrode 212 comprises a part of theelectrode layer 213. For instance, the electrode layer 213 comprises anAu-plated layer.

In this embodiment, the first obverse surface electrode 211 is a gateelectrode, whereas the second obverse surface electrode 212 is a sourceelectrode. In the direction x, the first obverse surface electrode 211is positioned on the left of the second obverse surface electrode 212.(Or, the second obverse surface electrode 212 is positioned on the rightof the first obverse surface electrode 211.) In the direction y, thefirst obverse surface electrode 211 is positioned on the lower side ofthe second obverse surface electrode 212. (Or, the second obversesurface electrode 212 is positioned on the upper side of the firstobverse surface electrode 211.) The reverse surface electrode 220 isformed on the reverse surface 202 of the element body. In thisembodiment, the reverse surface electrode 220 is a drain electrode.

A removal region 214 is formed by removing a part of the electrode layer213 formed on the obverse surface 201. The removal region 214 surroundsthe first obverse surface electrode 211. Specifically, as illustrated inFIG. 14, the removal region 214 includes two portions extending parallelto the upper edge of the semiconductor element 200 (and a connectingportion that connects the right ends of these portions to each other),two portions extending parallel to the right edge of the semiconductorelement 200 (and a connecting portion that connects the upper ends ofthese portions to each other), and two portions sandwiching the firstobverse surface electrode 211 in the neighborhood of the electrode. Withthese portions connected to each other, the removal region 214 surroundsthe first obverse surface electrode 211 without a break. Thecontinuously extending removal region 214 provides insulation betweenthe first obverse surface electrode 211 and the second obverse surfaceelectrode 212.

An active region 216 is provided adjacent to the second obverse surfaceelectrode 212. MOSFET 217 is built in the active region 216.Specifically, the MOSFET 217 is formed inside the element body (i.e., inthe inner portion spaced apart from the obverse surface 201 in thedirection z) and is made up of a plurality of unit cells 218. In theexample illustrated in FIG. 14, the unit cells 218 are arranged in amatrix (i.e., the unit cells are aligned in the vertical direction andthe horizontal direction). However, the present invention is not limitedto this, and the unit cells may be arranged in other manners. Forinstance, the unit cells may be arranged in rows or columns or in astaggered manner.

Although only the second obverse surface electrode 212 is provided asthe source electrode in this embodiment, the present invention is notlimited to this. For instance, a plurality of source electrodes may beprovided.

The semiconductor element 200 is arranged on the main lead 300. Asillustrated in FIGS. 2 and 3, as viewed in the thickness direction z,the semiconductor element 200 has portions that do not overlap the mainlead 300, i.e., portions that project outward beyond the outer edge ofthe main lead 300. As described later, the main lead 300 has portionsexposed from the resin package 800. In this embodiment, the main lead300 is formed by working a lead frame prepared in advance. That is, themain lead 300 is derived from the lead frame. For instance, the leadframe is formed by patterning a predetermined metal member (e.g. a platemade of Cu) by etching.

As illustrated in FIGS. 4 and 5, the main lead 300 has a main-leadobverse surface (die pad) 310 and a main-lead reverse surface (main-leadreverse surface terminal) 320 spaced apart from each other in thethickness direction z and facing in mutually opposite directions. Bothof the main-lead obverse surface 310 and the main-lead reverse surface320 are flat.

The main-lead obverse surface 310 faces upward in the thicknessdirection z. On the main-lead obverse surface 310 is placed thesemiconductor element 200. The main-lead obverse surface 310 is formedwith a main-lead obverse surface plating layer 311. The plating layer311 is positioned between the semiconductor element 200 and the mainlead 300. The plating layer 311 is formed over the entire region of themain-lead obverse surface 310. The plating layer 311 is about 2 μm inthickness and made of Ag.

In FIG. 3, the main-lead reverse surface 320 is indicated by hatching.The main-lead reverse surface 320 faces downward in the thicknessdirection z and is used for surface-mounting the semiconductor device101 on a mount object (e.g. printed circuit board). The main-leadreverse surface 320 is rectangular. The area of the main-lead reversesurface 320 is smaller than that of the main-lead obverse surface 310and the entirety of the main-lead reverse surface 320 overlaps themain-lead obverse surface 310 as viewed in the thickness direction z.That is, as viewed in the thickness direction z, the entirety of themain-lead reverse surface 320 is contained in the main-lead obversesurface 310.

The main lead 300 has a main-lead full-thickness portion 330 and amain-lead eaved portion 340.

The main-lead full-thickness portion 330 extends from the obversesurface 310 to the reverse surface 320 of the main lead in the thicknessdirection z. In this embodiment, the entirety of the full-thicknessportion 330 overlaps the semiconductor element 200 as viewed in thethickness direction z. In the present invention, it is only necessarythat at least one of the first obverse surface electrode 211 and thesecond obverse surface electrode 212 overlaps the full-thickness portion330 as viewed in the thickness direction z. In the example illustratedin FIG. 2, as viewed in the thickness direction z, the first obversesurface electrode 211 and the second obverse surface electrode 212 arearranged adjacent to the center of the semiconductor element 200, andboth of the first obverse surface electrode 211 and the second obversesurface electrode 212 overlap the full-thickness portion 330. Unlikethis embodiment, only the first obverse surface electrode 211 (or onlythe second obverse surface electrode 212) may overlap the full-thicknessportion 330 as viewed in the thickness direction z. For instance, thefull-thickness portion 330 is about 0.9-1.1 mm in thickness. Thefull-thickness portion 330 provides the reverse surface 320 of the mainlead.

The main-lead eaved portion 340 projects from the main-leadfull-thickness portion 330 in a direction perpendicular to the thicknessdirection z. In this embodiment, the eaved portion 340 projects from thefull-thickness portion 330 in the direction x and the direction y. Inthis embodiment, the eaved portion 340 projects in the direction x andthe direction y from a portion of the full-thickness portion 330adjacent to the main-lead obverse surface 310 (the portion adjacent tothe obverse surface 310). For instance, the thickness of the eavedportion 340 is half the thickness of the full-thickness portion 330 andabout 0.05 mm. The eaved portion 340 and the full-thickness portion 330provide the main-lead obverse surface 310. The eaved portion 340 doesnot provide the main-lead reverse surface 320 and is spaced apart fromthe reverse surface 320 in the thickness direction z. As viewed in thethickness direction z, the eaved portion 340 surrounds thefull-thickness portion 330. In this embodiment, the entirety of theeaved portion 340 overlaps the semiconductor element 200 as viewed inthe thickness direction z.

The main-lead eaved portion 340 has a main-lead front portion 341, twomain-lead side portions 342 and a main-lead rear portion 343. Themain-lead front portion 341 projects from the main-lead full-thicknessportion 330 toward the first sublead 400 and the second sublead 500.

Each of the main-lead side portions 342 projects from the full-thicknessportion 330 in a direction (the direction y) perpendicular to thedirection in which the main-lead front portion 341 projects. The mainlead 300 further includes two main-lead side connecting portions 351.Each of the side connecting portions 351 extends from a correspondingone of the side portions 342 and has the same thickness as the sideportion 342. The end surface of each side connecting portion 351 in thedirection y (the end surface facing in the direction y) is exposed fromthe resin package 800.

The main-lead rear portion 343 projects from the full-thickness portion330 in the direction opposite from the main-lead front portion 341. Inthis embodiment, the main lead 300 includes a main-lead rear connectingportion 352. The rear connecting portion 352 extends from the rearportion 343 of the main-lead eaved portion 340 and has the samethickness as the rear portion 343. The end surface of the rearconnecting portion 352 in the direction x (the end surface facing in thedirection x) is exposed from the resin package 800.

As illustrated in FIG. 6, the reverse surface electrode 220 of thesemiconductor element 200 is bonded to the main-lead obverse surface 310(main-lead obverse surface plating layer 311). Specifically, the reversesurface electrode 220 as a single metal layer is directly bonded to theplating layer 311 by e.g. thermocompression bonding. In thethermocompression bonding, only heat and pressure are applied andvibration is not applied.

The first sublead 400 is spaced apart from the main lead 300.Specifically, the first sublead 400 is spaced apart from the main lead300 in the direction x. The first sublead 400 is spaced apart from thesecond sublead 500. As viewed in the thickness direction z, the firstsublead 400 is exposed from the resin package 800 to the outside of theresin package 800. In this embodiment, the first sublead 400 is exposedfrom the resin package 800 in the direction x and the direction y.Similarly to the main lead 300, the first sublead 400 is derived from alead frame.

The first sublead 400 includes a first sublead obverse surface (firstwire bonding portion) 410, a first sublead reverse surface (firstsublead reverse surface terminal) 420, a first sublead end surface 481and a first sublead side surface 482. All of the obverse surface 410,the reverse surface 420, the end surface 481 and the side surface 482 ofthe first sublead are flat.

The first sublead obverse surface 410 faces upward in the thicknessdirection z. The first wire 600 is bonded to the obverse surface 410.The obverse surface 410 is formed with a first sublead obverse surfaceplating layer 411. The plating layer 411 is positioned between theobverse surface 410 and the first wire 600. The plating layer 411 isformed over the entire region of the obverse surface 410. For instance,the plating layer 411 is about 2 μm in thickness and made of Ag. In FIG.1, the plating layer 411 is illustrated in halftone for easierunderstanding.

The first sublead reverse surface 420 faces in the opposite directionfrom the first sublead obverse surface 410. Specifically, the firstsublead reverse surface 420 faces downward in the thickness direction z.The reverse surface 420 is exposed from the resin package 800. Thereverse surface 420 is used for surface-mounting the semiconductordevice 101. In FIG. 3, the reverse surface 420 is indicated by hatching.

The first sublead end surface 481 faces away from the main lead 300.Specifically, the end surface 481 faces to the right in FIG. 3. The endsurface 481 is connected to the first sublead reverse surface 420. Theend surface 481 is exposed from the resin package 800.

The first sublead side surface 482 faces in a direction perpendicular toboth of the direction in which the first sublead end surface 481 facesand the thickness direction z of the semiconductor element 200.Specifically, the side surface 482 faces downward in FIG. 3. The sidesurface 482 is connected to the first sublead reverse surface 420. Theside surface 482 is exposed from the resin package 800.

The first sublead 400 has a first sublead full-thickness portion 430 anda first sublead eaved portion 440. The full-thickness portion 430extends from the obverse surface 410 to the reverse surface 420 of thefirst sublead in the thickness direction z. In this embodiment, thefull-thickness portion 430 is about 0.1 mm in thickness. Thefull-thickness portion 430 provides the first sublead obverse surface410 and the first sublead reverse surface 420. The full-thicknessportion 430 is exposed from the resin package 800. Thus, thefull-thickness portion 430 provides the end surface 481 and the sidesurface 482 of the first sublead.

The first sublead eaved portion 440 projects from the first subleadfull-thickness portion 430 in a direction perpendicular to the thicknessdirection z. In this embodiment, the eaved portion 440 projects in thedirection x and the direction y. For instance, the thickness of theeaved portion 440 is half the thickness of the full-thickness portion430 and about 0.05 mm. The eaved portion 440 provides the obversesurface 410 of the first sublead. The eaved portion 440 does not providethe reverse surface 420 of the first sublead.

In this embodiment, the first sublead eaved portion 440 has a firstsublead front portion 441 and a first sublead inner portion 442.

The first sublead front portion 441 projects from the full-thicknessportion 430 toward the main lead 300. The inner portion 442 projectsfrom the full-thickness portion 430 toward the second sublead 500.

The second sublead 500 is spaced apart from the main lead 300.Specifically, the second sublead 500 is spaced apart from the main lead300 in the direction x. The second sublead 500 is spaced apart from thefirst sublead 400. As viewed in the thickness direction z, the secondsublead 500 is exposed from the resin package 800 to the outside of theresin package. In this embodiment, the second sublead 500 is exposedfrom the resin package 800 in the direction x and the direction y.Similarly to the main lead 300 and the first sublead 400, the secondsublead 500 is derived from a lead frame.

The second sublead 500 includes a second sublead obverse surface (secondwire bonding portion) 510, a second sublead reverse surface (secondsublead reverse surface terminal) 520, a second sublead end surface 581and a second sublead side surface 582. All of the obverse surface 510,the reverse surface 520, the end surface 581 and the side surface 582 ofthe second sublead are flat.

The second sublead obverse surface 510 faces upward in the thicknessdirection z. The second wire 700 is bonded to the obverse surface 510.In this embodiment, the obverse surface 510 is formed with a firstsublead obverse surface plating layer 511. The plating layer 511 ispositioned between the obverse surface 510 and the second wire 700. Theplating layer 511 is formed over the entire region of the obversesurface 510. For instance, the plating layer 511 is about 2 μm inthickness and made of Ag. In FIG. 1, the plating layer 511 isillustrated in halftone for easier understanding.

The second sublead reverse surface 520 faces in an opposite directionfrom the second sublead obverse surface 510. Specifically, the secondsublead reverse surface 520 faces downward in the thickness direction z.The reverse surface 520 is exposed from the resin package 800. Thereverse surface 520 is used for surface-mounting the semiconductordevice 101. In FIG. 3, the reverse surface 520 is indicated by hatching.

The second sublead end surface 581 faces away from the main lead 300.Specifically, the end surface 581 faces to the right in FIG. 3. The endsurface 581 is connected to the reverse surface 520 of the secondsublead. The end surface 581 is exposed from the resin package 800.

The second sublead side surface 582 faces in a direction perpendicularto both of the direction in which the second sublead end surface 581faces and the thickness direction z of the semiconductor element 200.Specifically, the side surface 582 faces upward in FIG. 3. The sidesurface 582 is connected to the reverse surface 520 of the firstsublead. The side surface 582 is exposed from the resin package 800.

The second sublead 500 has a second sublead full-thickness portion 530and a second sublead eaved portion 540. The full-thickness portion 530extends from the obverse surface 510 to the reverse surface 520 of thesecond sublead in the thickness direction z. In this embodiment, thefull-thickness portion 530 is about 0.1 mm in thickness. Thefull-thickness portion 530 provides the obverse surface 510 and thereverse surface 520 of the second sublead. The full-thickness portion530 is exposed from the resin package 800. Thus, the full-thicknessportion 530 provides the end surface 581 and the side surface 582 of thesecond sublead.

The second sublead eaved portion 540 projects from the second subleadfull-thickness portion 530 in a direction perpendicular to the thicknessdirection z. In this embodiment, the eaved portion 540 projects in thedirection x and the direction y. For instance, the thickness of theeaved portion 540 is half the thickness of the full-thickness portion530 and about 0.05 mm. The eaved portion 540 provides the obversesurface 510 of the second sublead. The eaved portion 540 does notprovide the reverse surface 520 of the second sublead.

In this embodiment, the second sublead eaved portion 540 has a secondsublead front portion 541 and a second sublead inner portion 542.

The second sublead front portion 541 projects from the full-thicknessportion 530 toward the main lead 300. The second sublead inner portion542 projects from the full-thickness portion 530 toward the firstsublead 400.

The first wire 600 is directly connected to the semiconductor element200 and electrically connects the semiconductor element 200 and thefirst sublead 400 to each other. Specifically, the first wire 600 isbonded to the first obverse surface electrode 211 of the semiconductorelement 200 and the obverse surface plating layer 411 of the firstsublead.

The first wire 600 has a first bonding portion 610 and a second bondingportion 620. The first wire 600 is about 20 μm in diameter and made ofAu.

The first bonding portion 610 is bonded to the obverse surface platinglayer 411 of the first sublead and has a crown-like lump portion.

The second bonding portion 620 is bonded to the first obverse surfaceelectrode 211 of the semiconductor element 200 via a first bump 630. Thesecond bonding portion 620 has a tapered shape and the thickness in thedirection z reduces as proceeding toward the end.

The first bump 630 is similar to the lump portion of the first bondingportion 610. In this embodiment, the volume of the first bump 630 isslightly smaller than that of the lump portion of the first bondingportion 610. As viewed in the thickness direction z, the first bump 630overlaps the main-lead full-thickness portion 330. FIG. 10 shows anenlarged image of the second bonding portion 620 of the semiconductordevice of FIG. 1.

The second wire 700 is directly connected to the semiconductor element200 and electrically connects the semiconductor element 200 and thesecond sublead 500 to each other. Specifically, the second wire 700 isbonded to the second obverse surface electrode 212 of the semiconductorelement 200 and the obverse surface plating layer 511 of the secondsublead.

The second wire 700 has a first bonding portion 710 and a second bondingportion 720. The second wire 700 is about 20 μm in diameter and made ofAu.

The first bonding portion 710 is bonded to the obverse surface platinglayer 511 of the second sublead and has a crown-like lump portion.

The second bonding portion 720 is bonded to the second obverse surfaceelectrode 212 of the semiconductor element 200 via a second bump 730.The second bonding portion 720 has a tapered shape and the thickness inthe direction z reduces as proceeding toward the end.

The second bump 730 is similar to the lump portion of the first bondingportion 710. As viewed in the thickness direction z, the second bump 730overlaps the main-lead full-thickness portion 330. In this embodiment,the volume of the second bump 730 is slightly smaller than that of thelump portion of the first bonding portion 710.

The resin package 800 covers the semiconductor element 200, the mainlead 300, the first sublead 400, the second sublead 500, the first wire600 and the second wire 700. For instance, the resin package 800 is madeof black epoxy resin. The resin package 800 exposes the reverse surface320 of the main lead 300, the reverse surface 420 of the first sublead400 and the reverse surface 520 of the second sublead 500 to the lowerside in the thickness direction z.

The resin package 800 has a resin obverse surface 801, a resin reversesurface 802, a first resin side surface 803, a second resin side surface804, a first resin end surface 805 and a second resin end surface 806.

The resin obverse surface 801 faces in the same direction as themain-lead obverse surface 310. In this embodiment, the resin obversesurface 801 is flat.

The resin reverse surface 802 faces in the same direction as themain-lead reverse surface 320. That is, the resin reverse surface 802faces in the opposite direction from the resin obverse surface 801. Theresin reverse surface 802 is flat. The main lead 300, the first sublead400 and the second sublead 500 are exposed from the resin reversesurface 802. The resin reverse surface 802 is flush with the main-leadreverse surface 320, the first sublead reverse surface 420 and thesecond sublead reverse surface 520.

The first resin side surface 803 faces in the same direction as the sidesurface 482 of the first sublead 400. The first resin side surface 803is flat. The first sublead 400 is exposed from the first resin sidesurface 803. The first sublead full-thickness portion 430 is exposedfrom the first resin side surface 803. The first resin side surface 803is flush with the first sublead side surface 482. The main lead 300 isexposed from the first resin side surface 803. Specifically, the sideconnecting portions 351 of the main lead 300 is exposed from the firstresin side surface 803. The first resin side surface 803 is flush withthe end surface of the main-lead side connecting portion 351.

The second resin side surface 804 faces in the same direction as theside surface 582 of the second sublead 500. The second resin sidesurface 804 is flat. The second sublead 500 is exposed from the secondresin side surface 804. The second resin side surface 804 is flush withthe second sublead side surface 582. In this embodiment, the secondsublead full-thickness portion 530 is exposed from second resin sidesurface 804. Moreover, the main lead 300 is exposed from the secondresin side surface 804. Specifically, the side connecting portions 351of the main lead 300 is exposed from the second resin side surface 804.The second resin side surface 804 is flush with the end surface of themain-lead side connecting portion 351.

The first resin end surface 805 faces in the same direction as the endsurface 481 of the first sublead 400. The first resin end surface 805 isflat. The first sublead 400 is exposed from the first resin end surface805. The first resin end surface 805 is flush with the first sublead endsurface 481. In this embodiment, the first sublead full-thicknessportion 430 is exposed from the first resin end surface 805. Similarly,the first resin end surface 805 faces in the same direction as the endsurface 581 of the second sublead 500. The second sublead 500 is exposedfrom the first resin end surface 805. The first resin end surface 805 isflush with the second sublead end surface 581. The second subleadfull-thickness portion 530 is exposed from the first resin end surface805.

The second resin end surface 806 faces in the opposite direction fromthe first resin end surface 805. The second resin end surface 806 isflat. The main lead 300 is exposed from the second resin end surface806. In this embodiment, the main-lead rear connecting portion 352 isexposed from the second resin end surface 806. The second resin endsurface 806 is flush with the end surface of the main-lead rearconnecting portion 352.

In the process of making the semiconductor device 101, a resin member tobecome the resin package and a lead frame are diced collectively. Thisis the reason why the above-described surfaces of the resin package andthe above-described surfaces of the leads (main lead 300, first sublead400 or the second sublead 500) are flush with each other. FIG. 11 is asectional view illustrating a step of a method for making thesemiconductor device of FIG. 1 and shows the portion adjacent to thefirst sublead 400. The lead and the resin member are cut along thecutting line Ct1 in this figure.

The advantages of the foregoing embodiment are described below.

The semiconductor element 200 includes portions that do not overlap themain lead 300 as viewed in the thickness direction z. With thisarrangement, the size of the main lead 300 is smaller than that of thesemiconductor element 200 as viewed in the thickness direction z. Thus,the size of the resin package 800 as viewed in the thickness direction zdepends not on the size of the main lead 300 but on the size of thesemiconductor element 200. Thus, the size of the semiconductor device101 as viewed in the thickness direction z can be reduced.

The main lead 300 includes a full-thickness portion 330 and an eavedportion 340. This arrangement provides a large bonding area between thesemiconductor element 200 and the main lead 300. Thus, the semiconductorelement 200 is reliably bonded to the main lead 300.

The second bonding portion 620 of the first wire 600 is bonded to thefirst obverse surface electrode 211 via the first bump 630, whereas thesecond bonding portion 720 of the second wire 700 is bonded to thesecond obverse surface electrode 212 via the second bump 730. Thisarrangement reduces the heights of the first wire 600 and the secondwire 700. This allows the dimension of the semiconductor device 101 inthe thickness direction z to be reduced. Thus, this embodiment achievessize reduction of the semiconductor device 101.

The first obverse surface electrode (gate electrode) 211 is positionedfurther away from the first sublead 400 and the second sublead 500 thanthe second obverse surface electrode (source electrode) 212 is. Thus,the first wire 600 can be made longer than the second wire 700. Thelonger first wire 600 can be easily bonded to the second bonding portion620 with higher bonding strength. The first obverse surface electrode211 as the gate electrode is formed on a relatively smooth surface ofthe semiconductor layer 231 via an insulating layer. Thus, it isrelatively difficult to bond a wire onto the first obverse surfaceelectrode 211 with a high bonding strength. On the other hand, thesecond obverse surface electrode 212 as the source electrode isconnected to a metal portion filling a plurality of trenches (verticalholes) formed in the semiconductor layer 231. Owing to this arrangement,it is relatively easy to bond a wire onto the second obverse surfaceelectrode 212 with a high bonding strength. Thus, bonding the first wire600, which can be bonded with higher bonding strength, to the firstobverse surface electrode 211, which is likely to lack the wire bondingstrength, is advantageous for preventing wire separation.

Since the main-lead eaved portion 340 has the front portion 341, thebonding strength between the main lead 300 and the resin package 800 isenhanced. Moreover, while the distance between the semiconductor element200 and the first sublead 400 or the second sublead 500 is reduced, themain-lead reverse surface 320 is prevented from being positioned tooclose to the first sublead reverse surface 420 and the second subleadreverse surface 520.

Since the main-lead eaved portion 340 has side portions 342 and the rearportion 343, the bonding strength between the main lead 300 and theresin package 800 is enhanced. The arrangement in which the entirety ofthe main-lead full-thickness portion 330 is surrounded by the main-leadeaved portion 340 is advantageous for enhancing the bonding strengthbetween the main lead 300 and the resin package 800.

The main-lead side connecting portions 351 and the main-lead rearconnecting portion 352 hold the main lead 300 properly during theprocess for making the semiconductor device 101. The end surface of themain-lead side connecting portion 351 in the direction y and the endsurface of the main-lead rear connecting portion 352 in the direction xare spaced apart from the main-lead reverse surface 320, though exposedfrom the resin package 800. Thus, solder for surface-mounting thesemiconductor device 101 does not spread onto the end surface of themain-lead side connecting portion 351 in the direction y and the endsurface of the main-lead rear connecting portion 352 in the direction x.

Since the main-lead obverse surface plating layer 311 is formed on themain-lead obverse surface 310, the bonding strength between the reversesurface electrode 220 of the semiconductor element 200 and the main-leadobverse surface 310 is enhanced. Since the main-lead obverse surfaceplating layer 311 overlaps the entirety of the main-lead eaved portion340, a large area can be used as the main-lead obverse surface 310.

Since the first sublead 400 has a first sublead eaved portion 440, thebonding strength between the first sublead 400 and the resin package 800is enhanced. Since the first sublead eaved portion 440 has the frontportion 441, the first sublead reverse surface 420 is prevented frombeing positioned too close to the main-lead reverse surface 320, whileenhanced bonding strength with the resin package 800 is provided. Thus,even when the semiconductor device 101 is made small, the first subleadreverse surface 420 and the main-lead reverse surface 320 are preventedfrom being electrically connected to each other by way of the solderadhering to the first sublead reverse surface 420 and the solderadhering to the main-lead reverse surface 320.

Since the first sublead eaved portion 440 has the first sublead innerportion 442, the bonding strength between the first sublead 400 and theresin package 800 is enhanced. Moreover, since the first sublead eavedportion 440 has the first sublead inner portion 442, the first subleadreverse surface 420 and the second sublead reverse surface 520 areprevented from being positioned too close to each other, while enhancedbonding strength with the resin package 800 is provided. Thus, even whenthe semiconductor device 101 is made small, the first sublead reversesurface 420 and the second sublead reverse surface 520 are preventedfrom being electrically connected to each other by way of the solderadhering to the first sublead reverse surface 420 and the solderadhering to the second sublead reverse surface 520.

The first sublead 400 has the end surface 481 connected to the reversesurface 420. The first sublead end surface 481 is exposed from the resinpackage 800. Thus, the first sublead reverse surface 420 can be madelarger. Thus, the tape 901 (see FIG. 11) used in a resin-molding processfor forming the resin package 800 and the first sublead reverse surface420 can be bonded strongly. Thus, during the resin molding, the resinmaterial is prevented from entering between the tape 901 and the firstsublead reverse surface 420. Thus, formation of resin burrs on the firstsublead reverse surface 420 is prevented. The arrangement that the firstsublead side surface 482 is exposed from the resin package 800 providesthe same advantages. Moreover, the same advantages as those related tothe first sublead 400 are provided by the arrangement that the secondsublead end surface 581 and the second sublead side surface 582 areexposed from the resin package 800.

Since the first sublead obverse surface plating layer 411 is formed onthe first sublead obverse surface 310, the bonding strength between thefirst wire 600 and the first sublead obverse surface 410 is enhanced.

Since the second sublead 500 has a second sublead eaved portion 540, thebonding strength between the second sublead 500 and the resin package800 is enhanced. Since the second sublead eaved portion 540 has thefront portion 541, the second sublead reverse surface 520 is preventedfrom being positioned too close to the main-lead reverse surface 320,while enhanced bonding strength with the resin package 800 is provided.

Since the second sublead eaved portion 540 has the second sublead innerportion 542, the bonding strength between the second sublead 500 and theresin package 800 is enhanced. Moreover, since the second sublead eavedportion 540 has the second sublead inner portion 542, the second subleadreverse surface 520 and the first sublead reverse surface 420 areprevented from being positioned too close to each other, while enhancedbonding strength with the resin package 800 is provided. Thus, even whenthe semiconductor device 101 is made small, the first sublead reversesurface 420 and the second sublead reverse surface 520 are preventedfrom being electrically connected to each other by way of the solderadhering to the first sublead reverse surface 420 and the solderadhering to the second sublead reverse surface 520.

Since the second sublead obverse surface plating layer 511 is formed onthe second sublead obverse surface 510, the bonding strength between thesecond wire 700 and the second sublead obverse surface 510 is enhanced.

The semiconductor element 200 is bonded to the obverse surface 310 ofthe main lead 300 by directly bonding the reverse surface electrode 220made of a single metal layer to the main-lead obverse surface platinglayer 311, and vibration is not applied in the bonding process. Thus, itis not necessary to provide the main lead 300 with an extra regionaround the semiconductor element 200 in consideration for theapplication of vibration. This is advantageous for size reduction of thesemiconductor device 101.

A semiconductor device according to a second embodiment of the presentinvention is described below with reference to FIGS. 12 and 13. Thesemiconductor device 102 illustrated in these figures differ from thesemiconductor device 101 of the first embodiment in shapes of the firstsublead 400 and the second sublead 500. Other elements that are theidentical or similar to those of the semiconductor device 101 aredesignated by the same reference signs as those used for the firstembodiment and explanation is omitted.

In the second embodiment, the first sublead 400 has an extension 460 inaddition to the full-thickness portion 430 and the eaved portion 440. Inthis embodiment, the full-thickness portion (the first subleadfull-thickness portion 430) is not exposed from the side surface of theresin package 800.

The first sublead extension 460 extends out from the first subleadfull-thickness portion 430 in a direction perpendicular to the thicknessdirection z. For instance, the thickness of the extension 460 is halfthe thickness of the full-thickness portion 430 and about 0.05 mm. Theextension 460 provides a part of the first sublead reverse surface 420.(Remaining portions of the first sublead reverse surface 420 areprovided by the full-thickness portion 430.) The extension 460 does notprovide the first sublead obverse surface 410. As viewed in thethickness direction z, the extension 460 is exposed from the sidesurfaces of the resin package 800 to the outside of the resin package800. Specifically, the extension 460 is exposed from the resin package800 in the direction x and the direction y. Thus, the extension 460provides the first sublead end surface 481 and the first sublead sidesurface 482.

In this embodiment, the first sublead extension 460 includes a firstsublead rear portion 461 and a first sublead side portion 462. The rearportion 461 projects from the first sublead full-thickness portion 430in a direction away from the main lead 300. The rear portion 461provides the first sublead end surface 481. The side portion 462projects from the full-thickness portion 430 in a direction away fromthe second sublead 500. The side portion 462 provides the first subleadside surface 482.

The second sublead 500 has a full-thickness portion 530, an eavedportion 540 and an extension 560. In this embodiment, the full-thicknessportion (the second sublead full-thickness portion 530) is not exposedfrom the side surface of the resin package 800.

The second sublead extension 660 extends out from the second subleadfull-thickness portion 530 in a direction perpendicular to the thicknessdirection z. For instance, the thickness of the extension 560 is halfthe thickness of the full-thickness portion 530 and about 0.05 mm. Theextension 560 provides a part of the second sublead reverse surface 520.(Remaining portions of the second sublead reverse surface 520 areprovided by the full-thickness portion 530.) The extension 560 does notprovide the second sublead obverse surface 510. As viewed in thethickness direction z, the extension 560 is exposed from the sidesurfaces of the resin package 800 to the outside of the resin package800. Specifically, the extension 560 is exposed from the resin package800 in the direction x and the direction y. Thus, the extension 560provides the second sublead end surface 581 and the second sublead sidesurface 582.

In this embodiment, the second sublead extension 560 includes a secondsublead rear portion 561 and a second sublead side portion 562. The rearportion 561 projects from the full-thickness portion 530 in a directionaway from the main lead 300. The rear portion 561 provides the secondsublead end surface 581. The side portion 562 projects from thefull-thickness portion 530 in a direction away from the first sublead400. The side portion 562 provides the second sublead side surface 582.

In the process of making the semiconductor device 102, the lead and theresin member are cut along the cutting lines Ct2 in FIG. 11, which isused for explaining the semiconductor device 101.

The advantages of the second embodiment are described below. Thisembodiment provides the following advantages in addition to theadvantages provided by the semiconductor device 101.

According to the second embodiment, in cutting the lead frame to providethe first sublead 400, a relatively thin portion is diced, and it is notnecessary to dice a relatively thick portion (the portion correspondingto the first sublead full-thickness portion 430). The amount of burrs tobe formed is proportional to the thickness of the lead frame that iscut. Thus, by cutting a relatively thin portion of the lead frame,formation of burrs is suppressed. Similarly, in the process of formingthe second sublead 500, a relatively thin portion of the lead frame iscut, so that formation of metal burrs is suppressed.

In the first and the second embodiments, when the main lead 300 and thefirst and the second subleads 400, 500 are pattern-formed by etching, aclear corner like those illustrated in FIGS. 1-13 is not formed at eachboundary between adjacent portions of each lead, and each boundary canbe a curved surface. Specifically, the boundary between thefull-thickness portion 330 and the eaved portion 340 of the main lead300, the boundary between the full-thickness portion 430 and the eavedportion 440 or the boundary between the eaved portion 440 and theextension 460 of the first sublead 400 can be a curved surface. Theboundary between the full-thickness portion 530 and the eaved portion540 or the boundary between the eaved portion 540 and the extension 560of the second sublead 500 can be a curved surface. In making a verysmall semiconductor device, such a curved surface tends to be formedinevitably during the etching process, against the intention of design.

FIG. 15 illustrates a variation of the semiconductor device 101 of thefirst embodiment (see FIG. 2). As illustrated in the figure, thepositions of the first obverse surface electrode 211, second obversesurface electrode 212, second bonding portions 620, 720, first bump 630and second bump 730 differ from those of the semiconductor device 101.In other points, the semiconductor device illustrated in FIG. 15 is thesame as the semiconductor device 101 of the first embodiment.

Specifically, in FIG. 2, the first obverse surface electrode 211 isoffset to the left on the semiconductor element 200, whereas the secondobverse surface electrode 212 is offset to the right on thesemiconductor element 200. In FIG. 2, the second bonding portion 620 andthe first bump 630 are offset to the left from the second bondingportion 720 and the second bump 730. On the other hand, in FIG. 15, thefirst obverse surface electrode 211 is offset to the right on thesemiconductor element 200, whereas the second obverse surface electrode212 is offset to the left on the semiconductor element 200. In FIG. 15,the second bonding portion 620 and the first bump 630 are offset to theright from the second bonding portion 720 and the second bump 730. Inthis way, in the present invention, the positions of the first obversesurface electrode 211 and the second obverse surface electrode 212 canbe changed.

FIGS. 16-24 illustrate a semiconductor device 103 according to a thirdembodiment of the present invention.

The semiconductor device 103 of this embodiment includes a semiconductorelement 200, a main lead 300, a first sublead 400, a second sublead 500,a first wire 600, a second wire 700 and a resin package 800. Thesemiconductor device 103 is configured as a relatively small device thatcan be surface-mounted and is e.g. about 0.8 mm in dimension in thedirection x, about 0.6 mm in dimension in the direction y and about 0.36mm in dimension in the direction z (thickness direction).

The semiconductor element 200 is configured as a transistor. Similarlyto the foregoing embodiment, the semiconductor element 200 may be otherkinds of semiconductor elements (e.g. diode).

The semiconductor element 200 includes an element body having an obversesurface 201 and a reverse surface 202 and is formed with a first obversesurface electrode 211, a second obverse surface electrode 212 and areverse surface electrode 220. The obverse surface 201 and the reversesurface 202 are spaced apart from each other in the direction z and facein mutually opposite directions. For instance, the semiconductor element200 is about 300 μm in dimension in the direction x and about 300 μm indimension in the direction y.

As illustrated in FIG. 25, the first obverse surface electrode 211 andthe second obverse surface electrode 212 are formed on the obversesurface 201 as a part of an electrode layer 213. For instance, theelectrode layer 213 comprises an Au-plated layer. The first obversesurface electrode 211 is a gate electrode, whereas the second obversesurface electrode 212 is a source electrode. As illustrated in FIG. 25or 18, in the direction x, the first obverse surface electrode 211 ispositioned on the left of the second obverse surface electrode 212. (Or,the second obverse surface electrode 212 is positioned on the right ofthe first obverse surface electrode 211.) In the direction y, the firstobverse surface electrode 211 is positioned on the lower side of thesecond obverse surface electrode 212. (Or, the second obverse surfaceelectrode 212 is positioned on the upper side of the first obversesurface electrode 211.) The reverse surface electrode 220 is formed onthe reverse surface 202. The reverse surface electrode 220 is a drainelectrode.

A removal region 214 is formed by removing a part of the electrode layer213. The removal region 214 surrounds the first obverse surfaceelectrode 211. Specifically, as illustrated in FIG. 25, the removalregion 214 includes two portions extending parallel to the upper edge ofthe semiconductor element 200 (and a connecting portion that connectsthe right ends of these portions to each other), two portions extendingparallel to the right edge of the semiconductor element 200 (and aconnecting portion that connects the upper ends of these portions toeach other), and two portions sandwiching the first obverse surfaceelectrode 211 in the neighborhood of the electrode. With these portionsconnected to each other, the removal region 214 completely surrounds thefirst obverse surface electrode 211. The removal region 214 in the formof an enclosure provides insulation between the first obverse surfaceelectrode 211 and the second obverse surface electrode 212.

An active region 216 is provided adjacent to the second obverse surfaceelectrode 212. A MOSFET 217 is built in the active region 216.Specifically, the MOSFET 217 is formed inside the element body (i.e., inthe inner portion spaced apart from the obverse surface 201 in thedirection z) and is made up of a plurality of unit cells 218. In theexample illustrated in FIG. 25, the unit cells 218 are arranged in amatrix (i.e., the unit cells are aligned in the vertical direction andthe horizontal direction). However, the present invention is not limitedto this, and the unit cells may be arranged in other manners. Forinstance, the unit cells may be arranged in rows or columns or in astaggered manner.

Although only the second obverse surface electrode 212 is provided asthe source electrode in this embodiment, the present invention is notlimited to this. For instance, a plurality of source electrodes may beprovided.

FIG. 21 illustrates the reverse surface electrode 220 and the nearbyportions of the semiconductor element 200. The semiconductor element 200of this embodiment has a semiconductor layer 231 and a eutectic layer232. The semiconductor layer 231 incorporates parts to function as atransistor and is made of e.g. Si. The eutectic layer 232 is made of aeutectic of a semiconductor forming the semiconductor layer 231 and ametal. In this embodiment, the eutectic layer 232 is made of a eutecticof Si and Au. The eutectic layer 232 is formed by an alloying processcomprising laminating an Au layer on the semiconductor layer 231followed by heating these layers. A reverse surface electrode 220 isformed under the eutectic layer 232 in the direction z. The reversesurface electrode 220 is provided by forming an Au layer (single metallayer) on the eutectic layer 232 by vapor deposition. For instance, thethickness of the eutectic layer 232 is about 1200 nm. The reversesurface electrode 220 is about 600 nm in thickness and thinner than theeutectic layer 232. In this embodiment, the reverse surface of theelement body refers to the surface 202 of the eutectic layer 232 whichfaces downward in the direction z.

The main lead 300 has a die pad 310, a main-lead reverse surfaceterminal 320, a main-lead full-thickness portion 330 and a main-leadeaved portion 340. The main lead 300 is formed by working a lead frameprepared in advance. That is, the main lead 300 is derived from the leadframe. The lead frame is formed by patterning a predetermined metalmember (e.g. plate made of Cu) by etching.

The die pad 310 faces upward in the direction z. The semiconductorelement 200 is mounted on the die pad 310. In this embodiment, the diepad 310 is rectangular and about 0.4 mm in dimension in the direction xand about 0.5 mm in dimension in the direction y. The die pad 310 isformed with a main-lead obverse surface plating layer 311. The platinglayer 311 is formed over the entire region of the die pad 310. Forinstance, the plating layer 311 is about 2 μm in thickness and made ofAg. In FIG. 16, the plating layer 311 is illustrated in halftone foreasier understanding.

The main-lead reverse surface terminal 320 faces in the oppositedirection from die pad 310, i.e., downward in the direction z and isused for surface-mounting the semiconductor device 103. The reversesurface terminal 320 is rectangular and about 0.18 mm in dimension inthe direction x and about 0.48 mm in dimension in the direction y. Asviewed in the direction z, the entirety of the terminal 320 overlaps thedie pad 310 and is contained in the die pad 310. In this embodiment, themain lead 300 is formed with a main-lead reverse surface plating layer321. The reverse surface plating layer 321 is formed on the main lead300 at a portion where the reverse surface terminal 320 is to be formed.For instance, the plating layer 321 is about 0.06 mm in thickness andmade of Ni, Sn, or an alloy containing these. In this embodiment, thelower surface of the plating layer 321 in the direction z is theterminal 320. The plating layer 321 may not be formed, and the terminal320 may be provided by the above-described portion made of Cu.

The main lead full-thickness portion 330 extends from the die pad 310 tothe main-lead reverse surface terminal 320 in the direction z. In thisembodiment, the full-thickness portion 330 refers to the portion made ofCu excluding the main-lead reverse surface plating layer 321 and isabout 0.1 mm in thickness. Similarly to the main-lead reverse surfaceterminal 320, the full-thickness portion 330 is about 0.18 mm indimension in the direction x and about 0.48 mm in dimension in thedirection y.

The main-lead eaved portion 340 projects in the direction x and thedirection y perpendicular to the direction z from a portion of the mainlead full-thickness portion 330 adjacent to the die pad 310. The uppersurface of the eaved portion 340 in the direction z is flush with thefull-thickness portion 330. In this embodiment, the eaved portion 340has a main-lead front portion 341, main-lead side portions 342 and amain-lead rear portion 343. For instance, the thickness of the eavedportion 340 is half the thickness of the full-thickness portion 330 andabout 0.05 mm.

The main-lead front portion 341 projects from the main leadfull-thickness portion 330 toward the first sublead 400 and the secondsublead 500 in the direction x. In this embodiment, the front portion341 is rectangular and about 0.21 mm in dimension in the direction x andabout 0.5 mm in dimension in the direction y.

The main-lead side portions 342 project from the main leadfull-thickness portion 330 in the direction y. In this embodiment, twoside portions 342 are provided. The side portions 342 are about 0.18 mmin dimension in the direction x and about 0.01 mm in dimension in thedirection y. The main lead 300 further includes two main-lead sideconnecting portions 351. Each of the side connecting portions 351extends from a corresponding one of the side portions 342 of the eavedportion 320 and has the same thickness as the side portion 342. The endsurface of each side connecting portion 351 in the direction y isexposed from the resin package 800. The side connecting portions 351 areabout 0.1 mm in dimension in the direction x and about 0.04 mm indimension in the direction y.

The main-lead rear portion 343 projects from the main-leadfull-thickness portion 330 in the direction opposite from the main-leadfront portion 341. The rear portion 343 is about 0.01 mm in dimension inthe direction x and about 0.5 mm in dimension in the direction y. Inthis embodiment, the main lead 300 includes two main-lead rearconnecting portion 352. The rear connecting portions 352 extend from therear portion 343 of the main-lead eaved portion 340 and have the samethickness as the rear portion 343. The end surfaces of the rearconnecting portions 352 in the direction x are exposed from the resinpackage 800. Each rear connecting portion 352 is about 0.04 mm indimension in the direction x and about 0.1 mm in dimension in thedirection y.

According to the above-described arrangement, as viewed in the directionz, the entirety of the main-lead full-thickness portion 330 issurrounded by the main-lead eaved portion 340. The upper surfaces of thefull-thickness portion 330 and the eaved portion 340 in the direction zprovide the die pad 310. The main lead obverse surface plating layer 311overlaps the entirety of the full-thickness portion 330 and the eavedportion 340. As illustrated in FIG. 18, as viewed in the direction z,about a half part of the semiconductor element 200 overlaps thefull-thickness portion 330 and the remaining half of the semiconductorelement 200 overlaps the front portion 341 of the main-lead eavedportion 340. The first obverse surface electrode 211 overlaps thefull-thickness portion 330, whereas the second obverse surface electrode212 overlaps the front portion 341 of the eaved portion 340.

As illustrated in FIG. 21, the reverse surface electrode 220 of thesemiconductor element 200 is bonded to die pad 310 (main-lead obversesurface plating layer 311). Specifically, the reverse surface electrode220 as a single metal layer is directly bonded to the plating layer 311by e.g. thermocompression bonding. In the thermocompression bonding,only heat and pressure are applied and vibration is not applied.

The first sublead 400 is spaced apart from the main lead 300 in thedirection x. The first sublead 400 includes a first wire bonding portion410, a first sublead reverse surface terminal 420, a first subleadfull-thickness portion 430 and a first sublead eaved portion 440.Similarly to the main lead 300, the first sublead 400 is derived from alead frame.

The first wire bonding portion 410 faces upward in the direction z. Thefirst wire 600 is bonded to the f first wire bonding portion 410. Inthis embodiment, the first wire bonding portion 410 is rectangular andabout 0.2 mm in dimension in the direction x and about 0.2 mm indimension in the direction y. The first wire bonding portion 410 isformed with a first sublead obverse surface plating layer 411. Theplating layer 411 is formed over the entire region of the first wirebonding portion 410. The plating layer 411 is e.g. about 2 μm inthickness and made of Ag. In FIG. 16, the plating layer 411 isillustrated in halftone for easier understanding.

The first sublead reverse surface terminal 420 faces in the oppositedirection from the first wire bonding portion 410, i.e., downward in thedirection z and is used for surface-mounting the semiconductor device103. The reverse surface terminal 420 is rectangular and about 0.18 mmin dimension in the direction x and about 0.13 mm in dimension in thedirection y. As viewed in the direction z, the entirety of the reversesurface terminal 420 overlaps the first wire bonding portion 410 and iscontained in the first wire bonding portion 410. In this embodiment, thefirst sublead 400 is formed with a first sublead reverse surface platinglayer 421. The reverse surface plating layer 421 is formed on the firstsublead 400 at a portion where the reverse surface terminal 420 is to beformed. For instance, the reverse surface plating layer 421 is about0.06 mm in thickness and made of Ni, Sn, or an alloy containing these.In this embodiment, the lower surface of the reverse surface platinglayer 421 in the direction z is the reverse surface terminal 420. Theplating layer 421 may not be formed, and the terminal 420 may beprovided by the above-described portion made of Cu.

The first sublead full-thickness portion 430 extends from the first wirebonding portion 410 to the first sublead reverse surface terminal 420 inthe direction z. In this embodiment, the full-thickness portion 430refers to the portion made of Cu excluding the first sublead reversesurface plating layer 421 and is about 0.1 mm in thickness. Similarly tothe first sublead reverse surface terminal 420, the full-thicknessportion 430 is about 0.18 mm in dimension in the direction x and about0.13 mm in dimension in the direction y.

The first sublead eaved portion 440 projects in the direction x and thedirection y perpendicular to the direction z from a portion of the firstsublead full-thickness portion 430 adjacent to the first wire bondingportion 410. The upper surface of the eaved portion 440 in the directionz is flush with the full-thickness portion 430. In this embodiment, theeaved portion 440 has a first sublead front portion 441, first subleadside portions 442 and a first sublead rear portion 443. For instance,the thickness of the eaved portion 440 is half the thickness of thefull-thickness portion 430 and about 0.05 mm.

The first sublead front portion 441 projects from the first subleadfull-thickness portion 430 toward the main lead 300 in the direction x.In this embodiment, the front portion 441 is about 0.01 mm in dimensionin the direction x and about 0.2 mm in dimension in the direction y.

The first sublead side portions 442 project from the first subleadfull-thickness portion 430 in the direction y. In this embodiment, twoside portions 442 are provided. The side portion 442 on the upper sidein the direction y in FIG. 18 projects toward the second sublead 500 andis about 0.2 mm in dimension in the direction x and about 0.06 mm indimension in the direction y. The side portion 442 on the lower side inthe direction y in FIG. 18 is about 0.2 mm in dimension in the directionx and about 0.01 mm in dimension in the direction y. The first sublead400 further includes a first sublead side connecting portion 451. Theside connecting portion 451 extends from the side portion 442 of theeaved portion 420 downward in the direction y and has the same thicknessas the side portion 442. The end surface of the side connecting portion451 in the direction y is exposed from the resin package 800. The sideconnecting portion 451 is about 0.1 mm in dimension in the direction xand about 0.04 mm in dimension in the direction y.

The first sublead rear portion 443 projects from the first subleadfull-thickness portion 430 in the direction opposite from the firstsublead front portion 441. The rear portion 443 is about 0.01 mm indimension in the direction x and about 0.14 mm in dimension in thedirection y. In this embodiment, the first sublead 400 includes a firstsublead rear connecting portion 452. The rear connecting portion 452extends from the rear portion 443 of the eaved portion 440 and has thesame thickness as the rear portion 443. The end surface of the rearconnecting portion 452 in the direction x is exposed from the resinpackage 800. The rear connecting portion 452 is about 0.04 mm indimension in the direction x and about 0.1 mm in dimension in thedirection y.

According to the above-described arrangement, as viewed in the directionz, the entirety of the first sublead full-thickness portion 430 issurrounded by the first sublead eaved portion 440. The upper surfaces ofthe full-thickness portion 430 and the eaved portion 440 in thedirection z provide the first wire bonding portion 410. The firstsublead obverse surface plating layer 411 overlaps the entirety of thefull-thickness portion 430 and the eaved portion 440.

The second sublead 500 is aligned with the first sublead 400 in thedirection y and spaced apart from the main lead 300 in the direction x.The second sublead includes a second wire bonding portion 510, a secondsublead reverse surface terminal 520, a second sublead full-thicknessportion 530 and a second sublead eaved portion 540. Similarly to themain lead 300 and the first sublead 400, the second sublead 500 isderived from the lead frame.

The second wire bonding portion 510 faces upward in the direction z. Thesecond wire 700 is bonded to the second wire bonding portion 510. Inthis embodiment, the second wire bonding portion 510 is rectangular andabout 0.2 mm in dimension in the direction x and about 0.2 mm indimension in the direction y. The second wire bonding portion 510 isformed with a second sublead obverse surface plating layer 511. Theplating layer 511 is formed over the entire region of the second wirebonding portion 510. The plating layer 511 is e.g. about 2 μm inthickness and made of Ag. In FIG. 16, the second sublead obverse surfaceplating layer 511 is illustrated in halftone for easier understanding.

The second sublead reverse surface terminal 520 faces in the oppositedirection from the second wire bonding portion 510, i.e., faces downwardin the direction z. The second sublead reverse surface terminal 520 isused for surface-mounting the semiconductor device 103. The reversesurface terminal 520 is rectangular and about 0.18 mm in dimension inthe direction x and about 0.13 mm in dimension in the direction y. Asviewed in the direction z, the entirety of the reverse surface terminal520 overlaps the second wire bonding portion 510 and is contained in thesecond wire bonding portion 510. In this embodiment, the second sublead500 is formed with a second sublead reverse surface plating layer 521.The reverse surface plating layer 521 is formed on the second sublead500 at a portion where the reverse surface terminal 520 is to be formed.For instance, the reverse surface plating layer 521 is about 0.06 mm inthickness and made of Ni, Sn, or an alloy containing these. In thisembodiment, the lower surface of the reverse surface plating layer 521in the direction z is the reverse surface terminal 520. The platinglayer 521 may not be formed, and the terminal 520 may be provided by theabove-described portion made of Cu.

The second sublead full-thickness portion 530 extends from the secondwire bonding portion 510 to the second sublead reverse surface terminal520 in the direction z. In this embodiment, the full-thickness portion530 refers to the portion made of Cu excluding the second subleadreverse surface plating layer 521 and is about 0.1 mm in thickness.Similarly to the second sublead reverse surface terminal 520, thefull-thickness portion 530 is about 0.18 mm in dimension in thedirection x and about 0.13 mm in dimension in the direction y.

The second sublead eaved portion 540 projects in the direction x and thedirection y perpendicular to the direction z from a portion of thesecond sublead full-thickness portion 530 adjacent to the second wirebonding portion 510. The upper surface of the eaved portion 540 in thedirection z is flush with the full-thickness portion 530. In thisembodiment, the eaved portion 540 has a second sublead front portion541, second sublead side portions 542 and a second sublead rear portion543. For instance, the thickness of the eaved portion 540 is half thethickness of the full-thickness portion 530 and about 0.05 mm.

The second sublead front portion 541 projects from the second subleadfull-thickness portion 530 toward the main lead 300 in the direction x.In this embodiment, the front portion 541 is about 0.01 mm in dimensionin the direction x and about 0.2 mm in dimension in the direction y.

The second sublead side portions 542 project from the second subleadfull-thickness portion 530 in the direction y. In this embodiment, twoside portions 542 are provided. The side portion 542 on the lower sidein the direction y in FIG. 18 projects toward the first sublead 400 andis about 0.2 mm in dimension in the direction x and about 0.06 mm indimension in the direction y. The side portion 542 on the upper side inthe direction y in FIG. 18 is about 0.2 mm in dimension in the directionx and about 0.01 mm in dimension in the direction y. In this embodiment,the second sublead 500 further includes a second sublead side connectingportion 551. The side connecting portion 551 extends from the sideportion 542 of the eaved portion 540 upward in the direction y in FIG.18 and has the same thickness as the side portion 542. The end surfaceof the side connecting portion 551 in the direction y is exposed fromthe resin package 800. The side connecting portion 551 is about 0.1 mmin dimension in the direction x and about 0.04 mm in dimension in thedirection y.

The second sublead rear portion 543 projects from the second subleadfull-thickness portion 530 in the direction opposite from the secondsublead front portion 541. The rear portion 543 is about 0.01 mm indimension in the direction x and about 0.14 mm in dimension in thedirection y. In this embodiment, the second sublead 500 includes asecond sublead rear connecting portion 552. The rear connecting portion552 extends from the rear portion 543 of the eaved portion 540 and hasthe same thickness as the rear portion 543. The end surface of the rearconnecting portion 552 in the direction x is exposed from the resinpackage 800. The rear connecting portion 552 is about 0.04 mm indimension in the direction x and about 0.1 mm in dimension in thedirection y.

In this arrangement, as viewed in the direction z, the entirety of thesecond sublead full-thickness portion 530 is surrounded by the secondsublead eaved portion 540. The upper surfaces of the full-thicknessportion 530 and eaved portion 540 in the direction z provide the secondwire bonding portion 510. The second sublead obverse surface platinglayer 511 overlaps the entirety of the full-thickness portion 530 andthe eaved portion 540.

The first wire 600 is bonded to the first obverse surface electrode 211of the semiconductor element 200 and the first wire bonding portion 410of the first sublead 400. The first wire 600 has a first bonding portion610 and a second bonding portion 620. The first wire 600 is about 20 μmin diameter and made of Au.

The first bonding portion 610 is bonded to the first wire bondingportion 410 of the first sublead 400 and has a crown-like lump portion.The second bonding portion 620 is bonded to the first obverse surfaceelectrode 211 of the semiconductor element 200 via a first bump 630. Thesecond bonding portion 620 has a tapered shape and the thickness in thedirection z reduces as proceeding toward the end. The first bump 630 issimilar to the lump portion of the first bonding portion 610. In thisembodiment, the volume of the first bump 630 is slightly smaller thanthat of the lump portion of the first bonding portion 610.

The second wire 700 is bonded to the second obverse surface electrode212 of the semiconductor element 200 and the second wire bonding portion510 of the second sublead 500. The second wire 700 has a first bondingportion 710 and a second bonding portion 720. The second wire 700 isabout 20 μm in diameter and made of Au.

The first bonding portion 710 is bonded to the second wire bondingportion 510 of the second sublead 500 and has a crown-like lump portion.The second bonding portion 720 is bonded to the second obverse surfaceelectrode 212 of the semiconductor element 200 via a second bump 730.The second bonding portion 720 has a tapered shape and the thickness inthe direction z reduces as proceeding toward the end. The second bump730 is similar to the lump portion of the first bonding portion 710. Inthis embodiment, the volume of the second bump 730 is slightly smallerthan that of the lump portion of the first bonding portion 710.

The resin package 800 is made of e.g. black epoxy resin and covers thesemiconductor element 200 and portions of the main lead 300, firstsublead 400 and second sublead 500. The resin package 800 exposes thereverse surface terminal 320 of the main lead 300, the reverse surfaceterminal 420 of the first sublead 400 and the reverse surface terminal520 of the second sublead 500 to the lower side in the thicknessdirection z. In this embodiment, the distance between the upper ends ofthe first wire 600 and the second wire 700 in the direction z and theupper end of the resin package 800 in the direction z is about 50 μm.

An example of a method for making the semiconductor device 103 isdescribed below with reference to FIGS. 26-33. Only the process forbonding the first wire 600 is described with reference to FIGS. 26-32.The second wire 700 is bonded in a similar way. First, as illustrated inFIG. 26, the semiconductor element 200 is bonded to the main lead 300.In this step, the manufacturing efficiency is enhanced by using a leadframe including a plurality of main leads 300, first subleads 400 andsecond subleads 500. With a wire 601 exposed from the end of a capillaryCp, a spark is generated directly above the first obverse surfaceelectrode 211 of the semiconductor element 200. Thus, a ball 602 isformed at the end of the wire 601. The wire 601 is about 20 μm indiameter and made of Au.

Then, as illustrated in FIG. 27, the capillary Cp is moved downward,whereby the ball 602 is bonded to the first obverse surface electrode211 of the semiconductor element 200. Then, with the wire 601 fixedrelative to the capillary Cp, the capillary Cp is moved upward. Thus, asillustrated in FIG. 28, a first bump 630 is formed on the first obversesurface electrode 211.

Then, as illustrated in FIG. 29, a new ball 602 is formed at the end ofthe wire 601 by generating a spark directly above the first wire bondingportion 410 of the first sublead 400. Then, as illustrated in FIG. 30,the capillary Cp is moved downward, whereby the ball 602 is bonded tothe first wire bonding portion 410 of the first sublead 400.

Then, with the wire 601 unfixed relative to the capillary Cp, thecapillary Cp is moved along the path indicated by double-dashed lines inFIG. 31. Thus, while the first bonding portion 610 is formed, the wire601 is bent at a predetermined height and extended in the horizontaldirection. Then, the end of the capillary Cp is pressed against thefirst bump 630. In this process, the wire 601 is sandwiched between thecapillary Cp and the first bump 630, and the sandwiched portion isbonded to the first bump 630. (Alternatively, for instance, heat andvibration may be applied to the portion to be bonded via a support base,not shown, supporting the main lead 300). Then, with the wire 601 fixedrelative to the capillary Cp, the capillary Cp is separated from thesemiconductor element 200. In this way, the second bonding portion 620is formed. FIG. 32 is an enlarged image of the second bonding portion620 and the first bump 630 captured from above in the direction z. Asshown in the figure, the second bonding portion 620 that is slightlywidened is bonded onto the first bump 630 that is circular as viewed inplan.

Then, the second wire 700 is bonded in the same way as the first wire.Thereafter, a resin member in the form of a plate is made using e.g. ablack epoxy resin so as to cover the semiconductor element 200, thefirst wire 600, the second wire 700 and a part of each of the main lead300, first sublead 400 and second sublead 500. FIG. 33 illustrates theabove-described lead frame, semiconductor element 200, first wire 600and second wire 700. These elements are covered by the above-describedresin member (not shown). By cutting the resin member and the lead framecollectively along the cutting line CL in the figure, the semiconductordevice 103 illustrated in FIGS. 16-24 is obtained.

Advantages of the semiconductor device 103 are described below.

In this embodiment, the die pad 310 and the semiconductor element 200overlap both of the main-lead full-thickness portion 330 and main-leadeaved portion 340 as viewed in the direction z. The eaved portion 340functions to enhance the bonding strength between the main lead 300 andthe resin package 800. In this embodiment, the main lead 300 does notproject excessively from the semiconductor element 200, so that thedimension of the semiconductor device 103 as viewed in the direction zis reduced. The dimension of the semiconductor device 103 in thedirection z can be reduced by arranging at least one of the firstobverse surface electrode 211 and the second obverse surface electrode212 in such a manner as to overlap the main-lead eaved portion 340. Inthis embodiment, the second bonding portion 620 of the first wire 600 isbonded to the first obverse surface electrode 211 via the first bump630, and the second bonding portion 720 of the second wire 700 is bondedto the second obverse surface electrode 212 via the second bump 730. Bythis arrangement, each of the second bonding portions is properly fixedto a corresponding one of the obverse surface electrodes.

As illustrated in FIGS. 19 and 20, the first wire 600 and the secondwire 700 include portions that extend from the corresponding secondbonding portions 620, 720 generally straight in the lateral direction(the direction x) and do not include an arcuate portion projectingupward at a position higher than the second bonding portions. By thisarrangement, the heights of the first wire 600 and the second wire 700in the direction z are reduced. This contributes to reduction in size ofthe semiconductor device 103 in the direction z.

The first obverse surface electrode (gate electrode) 211 is positionedfurther away from the first sublead 400 and the second sublead 500 thanthe second obverse surface electrode (source electrode) 212 is. Thus,the first wire 600 can be made longer than the second wire 700. Thelonger first wire 600 can be easily bonded to the bonding portion(second bonding portion 620 in particular) with higher bonding strength.Generally, the gate electrode (the first obverse surface electrode 211in this embodiment) is formed on a relatively smooth surface of thesemiconductor layer via an insulating layer. Thus, it is relativelydifficult to bond a wire onto the gate electrode with a high bondingstrength. On the other hand, the source electrode (the second obversesurface electrode 212 in this embodiment) is connected to a metalportion filling a plurality of trenches (vertical holes) formed in asemiconductor layer. Owing to this arrangement, it is relatively easy tobond a wire onto the source electrode with a high bonding strength.Thus, bonding the first wire 600, which can be bonded with a higherbonding strength, to the first obverse surface electrode 211 (gateelectrode), which is likely to lack the wire bonding strength, isadvantageous for preventing wire separation.

Since the first obverse surface electrode 211 overlaps the main-leadfull-thickness portion 330 as viewed in the direction z, as describedwith reference to FIGS. 27 and 31, the capillary Cp can be reliablypressed against the first obverse surface electrode 211 as a gateelectrode, which is likely to lack bonding strength. The second obversesurface electrode 212 as a source electrode for which the bondingstrength is enhanced relatively easily is arranged at a positionoverlapping the main-lead eaved portion 340 as viewed in the directionz. This arrangement allows reduction in dimension of the semiconductordevice 103 as viewed in the direction z.

Since the main-lead eaved portion 340 has the front portion 341, thebonding strength between the main lead 300 and the resin package 800 isenhanced. Moreover, while the distance between the semiconductor element200 and the first sublead 400 or the second sublead 500 is reduced, themain-lead reverse surface terminal 320 is prevented from beingpositioned too close to the first sublead reverse surface terminal 420and the second sublead reverse surface terminal 520.

Since the main-lead eaved portion 340 has side portions 342 and the rearportion 343, the bonding strength between the main lead 300 and theresin package 800 is enhanced. The arrangement in which the entirety ofthe main-lead full-thickness portion 330 is surrounded by the main-leadeaved portion 340 is advantageous for enhancing the bonding strengthbetween the main lead 300 and the resin package 800.

The main-lead side connecting portions 351 and the main-lead rearconnecting portion 352 hold the main lead 300 properly during theprocess for manufacturing the semiconductor device 103. The end surfaceof the main-lead side connecting portion 351 in the direction y and theend surface of the main-lead rear connecting portion 352 in thedirection x are spaced apart from the main-lead reverse surface terminal320 though exposed from the resin package 800. Thus, solder forsurface-mounting the semiconductor device 103 does not spread onto theend surface of the main-lead side connecting portion 351 in thedirection y and the end surface of the main-lead rear connecting portion352 in the direction x.

Since the main-lead obverse surface plating layer 311 is formed on thedie pad 310, the bonding strength between the reverse surface electrode220 of the semiconductor element 200 and the die pad 310 is enhanced.Since the main-lead obverse surface plating layer 311 overlaps theentirety of the main-lead eaved portion 340, a large area can be used asthe die pad 310.

Since the first sublead 400 has the first sublead eaved portion 440, thebonding strength between the first sublead 400 and the resin package 800is enhanced. Since the first sublead eaved portion 440 has the frontportion 441, the first sublead reverse surface terminal 420 is preventedfrom being positioned too close to the main-lead reverse surfaceterminal 320, while enhanced bonding strength with the resin package 800is provided.

Since the first sublead eaved portion 440 has the first sublead sideportions 442 and the first sublead rear portion 443, the bondingstrength between the first sublead 400 and the resin package 800 isenhanced. The arrangement in which the entirety of the first subleadfull-thickness portion 430 is surrounded by the first sublead eavedportion 440 is advantageous for enhancing the bonding strength betweenthe first sublead 400 and the resin package 800. Since the side portion442 closer to the second sublead 500 is relatively large, the firstsublead reverse surface terminal 420 and the second sublead reversesurface terminal 520 are prevented from being positioned too close toeach other, while enhanced bonding strength is provided.

The first sublead side connecting portions 451 and the first subleadrear connecting portion 452 hold the first sublead 400 properly duringthe process for manufacturing the semiconductor device 103. The endsurface of the side connecting portion 451 in the direction y and theend surface of the rear connecting portion 452 in the direction x arespaced apart from the first sublead reverse surface terminal 420 thoughexposed from the resin package 800. Thus, solder for surface-mountingthe semiconductor device 103 does not spread onto the end surface of theside connecting portion 451 in the direction y and the end surface ofthe rear connecting portion 452 in the direction x.

Since the first sublead obverse surface plating layer 411 is formed onthe first wire bonding portion 410, the bonding strength between thefirst wire 600 and the first wire bonding portion 410 is enhanced.

Since the second sublead 500 has the second sublead eaved portion 540,the bonding strength between the second sublead 500 and the resinpackage 800 is enhanced. Since the second sublead eaved portion 540 hasthe front portion 541, the second sublead reverse surface terminal 520is prevented from being positioned too close to the main-lead reversesurface terminal 320, while enhanced bonding strength with the resinpackage 800 is provided.

Since the second sublead eaved portion 540 has the second sublead sideportions 542 and the second sublead rear portion 543, the bondingstrength between the second sublead 500 and the resin package 800 isenhanced. The arrangement in which the entirety of the second subleadfull-thickness portion 530 is surrounded by the second sublead eavedportion 540 is advantageous for enhancing the bonding strength betweenthe second sublead 500 and the resin package 800. Since the side portion542 closer to the first sublead 400 is relatively large, the secondsublead reverse surface terminal 520 and the first sublead reversesurface terminal 420 are prevented from being positioned too close toeach other, while enhanced bonding strength is provided.

The second sublead side connecting portions 551 and the second subleadrear connecting portion 552 hold the second sublead 500 properly duringthe process for manufacturing the semiconductor device 103. The endsurface of the side connecting portion 551 in the direction y and theend surface of the rear connecting portion 552 in the direction x arespaced apart from the second sublead reverse surface terminal 520 thoughexposed from the resin package 800. Thus, solder for surface-mountingthe semiconductor device 103 does not spread on the end surface of theside connecting portion 551 in the direction y and the end surface ofthe rear connecting portion 552 in the direction x.

Since the second sublead obverse surface plating layer 511 is formed onthe second wire bonding portion 510, the bonding strength between thesecond wire 700 and the second wire bonding portion 510 is enhanced.

The semiconductor element 200 is bonded to the die pad 310 of the mainlead 300 by directly bonding the reverse surface electrode 220 made of asingle metal layer to the main-lead obverse surface plating layer 311,and vibration is not applied in the bonding process. Thus, it is notnecessary to provide the main lead 300 with an extra region around thesemiconductor element 200 in consideration for the application ofvibration. This is advantageous for size reduction of the semiconductordevice 103.

FIG. 34 is an X-ray image of the semiconductor device 103. As shown inthe figure, when the main lead 300 and the first and the second subleads400, 500 are pattern-formed by etching, the boundary between themain-lead full-thickness portion 330 and the main-lead eaved portion 340can be a curved surface. Similarly, the boundary between the firstsublead full-thickness portion 430 and the first sublead eaved portion440 or the boundary between the second sublead full-thickness portion530 and the second sublead eaved portion 540 can be a curved surface. Inmaking a very small semiconductor device, such a curved surface tends tobe formed inevitably during the etching process, against the intentionof design (see configuration illustrated in FIGS. 16-24).

FIG. 35 illustrates a semiconductor device 104 according to a fourthembodiment of the present invention. In this figure, the elements thatare identical or similar to those of the third embodiment are designatedby the same reference signs as those used for the third embodiment.

In this embodiment, the first obverse surface electrode 211 overlapsboth of the main-lead full-thickness portion 330 and the main-lead eavedportion 340 as viewed in the direction z. As viewed in the direction z,the first bump 630 and the second bonding portion 620 of the first wire600 overlap both of the full-thickness portion 330 and the eaved portion340. In this figure, a chain line extending in the direction y crossesthe first bump 630 and the second bonding portion 620 of the first wire600. This chain line is the boundary between the full-thickness portion330 and the eaved portion 340 as viewed in the direction z. According tothis embodiment again, size reduction of the semiconductor device 104 isachieved.

The semiconductor device according to the present invention is notlimited to the foregoing embodiments. The specific structure of eachpart of the semiconductor device according to the present invention canbe varied in design in many ways. For instance, the semiconductorelement used for the semiconductor device according to the presentinvention is not limited to a transistor, and various kinds ofsemiconductor elements having two surface electrodes can be employed.

The invention claimed is:
 1. A semiconductor device comprising: asemiconductor element including an element body having an obversesurface and a reverse surface that are opposite to each other in athickness direction, the obverse surface being provided with an obverseelectrode, the reverse surface being provided with a reverse electrode;a lead supporting the semiconductor element; and a resin packagecovering the semiconductor element and the lead, wherein thesemiconductor element includes an portion that does not overlap with thelead as viewed in the thickness direction, the reverse electrode iselectrically connected to the lead, and the reverse electrode is made upof a single metal layer held in contact with the lead.
 2. Thesemiconductor device according to claim 1, wherein the lead has a leadobverse surface and a lead reverse surface that are opposite to eachother, the semiconductor element is disposed on the lead obversesurface, and the lead reverse surface is exposed from the resin package.3. The semiconductor device according to claim 1, further comprising anadditional lead connected to the semiconductor element, wherein at leasta part of the additional lead is exposed from the resin package.
 4. Thesemiconductor device according to claim 3, wherein the additional leadhas an obverse surface and a reverse surface that are spaced apart fromeach other in the thickness direction, and the reverse surface of theadditional lead is exposed from the resin package.
 5. A semiconductordevice according to claim 1, wherein comprising: a semiconductor elementincluding an element body having an obverse surface and a reversesurface that are opposite to each other in a thickness direction, theobverse surface being provided with an obverse electrode, the reversesurface being provided with a reverse electrode; a lead supporting thesemiconductor element; and a resin package covering the semiconductorelement and the lead, wherein the semiconductor element includes anportion that does not overlap with the lead as viewed in the thicknessdirection, the reverse electrode is electrically connected to the lead,and the element body includes a semiconductor layer and a eutectic layerheld in contact with the semiconductor layer, and the reverse electrodeis held in contact with the eutectic layer.
 6. The semiconductor deviceaccording to claim 5, wherein the reverse electrode and the eutecticlayer have respective end faces that are flush with each other and heldin contact with the resin package.
 7. The semiconductor device accordingto claim 5, wherein the semiconductor layer is formed with a portionfunctioning as a transistor.
 8. The semiconductor device according toclaim 5, wherein the reverse electrode is smaller in thickness than theeutectic layer.
 9. The semiconductor device according to claim 5,wherein the eutectic layer is made of a eutectic of a semiconductormaterial and a metal material.
 10. The semiconductor device according toclaim 9, wherein the semiconductor material is Si, and the metalmaterial is Au.
 11. A semiconductor device comprising: a semiconductorelement including an element body having an obverse surface and areverse surface that are opposite to each other in a thicknessdirection, the obverse surface being provided with an obverse electrode,the reverse surface being provided with a reverse electrode; a leadsupporting the semiconductor element; and a resin package covering thesemiconductor element and the lead, wherein the semiconductor elementincludes an portion that does not overlap with the lead as viewed in thethickness direction, the reverse electrode is electrically connected tothe lead, and the lead includes a plated layer held in contact with thereverse electrode.
 12. The semiconductor device according to claim 11,wherein the reverse electrode is attached to the plated layer bythermocompression.
 13. A semiconductor device comprising: asemiconductor element including an element body having an obversesurface and a reverse surface that are opposite to each other in athickness direction, the obverse surface being provided with an obverseelectrode, the reverse surface being provided with a reverse electrode;a lead supporting the semiconductor element; and a resin packagecovering the semiconductor element and the lead, wherein thesemiconductor element includes an portion that does not overlap with thelead as viewed in the thickness direction, the reverse electrode iselectrically connected to the lead, the lead has a lead obverse surfaceand a lead reverse surface that are opposite to each other, thesemiconductor element is disposed on the lead obverse surface, and thelead reverse surface is exposed from the resin package, and the leadincludes a full-thickness portion and an eaved portion, thefull-thickness portion extends from the lead obverse surface to the leadreverse surface, and the eaved portion projects from the full-thicknessportion in a direction perpendicular to the thickness direction.
 14. Thesemiconductor device according to claim 13, wherein an entirety of thefull-thickness portion overlaps with the semiconductor element as viewedin the thickness direction.
 15. The semiconductor device according toclaim 14, wherein an entirety of the eaved portion overlaps with thesemiconductor element as viewed in the thickness direction.
 16. Thesemiconductor device according to claim 13, wherein at least a part ofthe eaved portion has an end face exposed from the resin package.
 17. Asemiconductor device comprising: a semiconductor element including anelement body having an obverse surface and a reverse surface that areopposite to each other in a thickness direction, the obverse surfacebeing provided with an obverse electrode, the reverse surface beingprovided with a reverse electrode; a lead supporting the semiconductorelement; and a resin package covering the semiconductor element and thelead, wherein the semiconductor element includes an portion that doesnot overlap with the lead as viewed in the thickness direction, thereverse electrode is electrically connected to the lead, thesemiconductor device further comprises an additional lead connected tothe semiconductor element, wherein at least a part of the additionallead is exposed from the resin package, the additional lead has anobverse surface and a reverse surface that are spaced apart from eachother in the thickness direction, and the reverse surface of theadditional lead is exposed from the resin package, and the additionallead includes a full-thickness portion and an eaved portion, thefull-thickness portion extends from the obverse surface of theadditional lead to the reverse surface of the additional lead, and theeaved portion projects from the full-thickness portion in a directionperpendicular to the thickness direction.
 18. A semiconductor devicecomprising: a semiconductor element including an element body having anobverse surface and a reverse surface that are opposite to each other ina thickness direction, the obverse surface being provided with anobverse electrode, the reverse surface being provided with a reverseelectrode; a lead supporting the semiconductor element; and a resinpackage covering the semiconductor element and the lead, wherein thesemiconductor element includes an portion that does not overlap with thelead as viewed in the thickness direction, the reverse electrode iselectrically connected to the lead, the semiconductor device furthercomprises an additional lead connected to the semiconductor element,wherein at least a part of the additional lead is exposed from the resinpackage, and the semiconductor device further comprises a wireconnecting the semiconductor element to the additional lead, wherein thewire has an end connected to the obverse electrode of the semiconductorelement.
 19. The semiconductor device according to claim 18, furthercomprising a plated layer disposed between the additional lead andanother end of the wire.